SLA_GBRCOND Estimates the Skeel condition number of  op(A) * op2(C)


    where op2 is determined by CMODE as follows


    CMODE =  1    op2(C) = C


    CMODE =  0    op2(C) = I


    CMODE = -1    op2(C) = inv(C)


    The Skeel condition number  cond(A) = norminf( |inv(A)||A| )


    is computed by computing scaling factors R such that


    diag(R)*A*op2(C) is row equilibrated and computing the standard


    infinity-norm condition number.

TRANS

          TRANS is CHARACTER*1


     Specifies the form of the system of equations:


       = 'N':  A * X = B     (No transpose)


       = 'T':  A**T * X = B  (Transpose)


       = 'C':  A**H * X = B  (Conjugate Transpose = Transpose)

N

          N is INTEGER


     The number of linear equations, i.e., the order of the


     matrix A.  N >= 0.

KL

          KL is INTEGER


     The number of subdiagonals within the band of A.  KL >= 0.

KU

          KU is INTEGER


     The number of superdiagonals within the band of A.  KU >= 0.

AB

          AB is REAL array, dimension (LDAB,N)


     On entry, the matrix A in band storage, in rows 1 to KL+KU+1.


     The j-th column of A is stored in the j-th column of the


     array AB as follows:


     AB(KU+1+i-j,j) = A(i,j) for max(1,j-KU)<=i<=min(N,j+kl)

LDAB

          LDAB is INTEGER


     The leading dimension of the array AB.  LDAB >= KL+KU+1.

AFB

          AFB is REAL array, dimension (LDAFB,N)


     Details of the LU factorization of the band matrix A, as


     computed by SGBTRF.  U is stored as an upper triangular


     band matrix with KL+KU superdiagonals in rows 1 to KL+KU+1,


     and the multipliers used during the factorization are stored


     in rows KL+KU+2 to 2*KL+KU+1.

LDAFB

          LDAFB is INTEGER


     The leading dimension of the array AFB.  LDAFB >= 2*KL+KU+1.

IPIV

          IPIV is INTEGER array, dimension (N)


     The pivot indices from the factorization A = P*L*U


     as computed by SGBTRF; row i of the matrix was interchanged


     with row IPIV(i).

CMODE

          CMODE is INTEGER


     Determines op2(C) in the formula op(A) * op2(C) as follows:


     CMODE =  1    op2(C) = C


     CMODE =  0    op2(C) = I


     CMODE = -1    op2(C) = inv(C)

C

          C is REAL array, dimension (N)


     The vector C in the formula op(A) * op2(C).

INFO

          INFO is INTEGER


       = 0:  Successful exit.


     i > 0:  The ith argument is invalid.

WORK

          WORK is REAL array, dimension (5*N).


     Workspace.

IWORK

          IWORK is INTEGER array, dimension (N).


     Workspace.

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

December 2016